Test equipment is used to test performance of a test specimen in response to dynamic forces and motion imparted to the test specimen during various operating conditions. Such test equipment utilizes various actuators and devices to input force to the specimen. Typically, for a vehicle test apparatus input force or motion corresponds to road or steer input imparted to the vehicle through the vehicle suspension. Various other forces such as aerodynamic forces act on the vehicle during operation. Unlike road and steer forces, it is difficult to measure and quantify aerodynamic forces on the body imparted during operation of the vehicle.